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Evolution of O Abundance Relative to Fe

Qian, Y.-Z. and Wasserburg, G. J. (2001) Evolution of O Abundance Relative to Fe. Astrophysical Journal, 549 (1). pp. 337-345. ISSN 0004-637X.

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We present a three-component mixing model for the evolution of O abundance relative to Fe, taking into account the contributions of the first very massive stars (with masses of ≳100 M_☉) formed from Big Bang debris. We show that the observations of O and Fe abundances in metal-poor stars in the Galaxy by Israelian et al. in 1998 and by Boesgaard et al. in 1999 can be well represented both qualitatively and quantitatively by this model. We use the representation of the number ratios (O/Fe) versus 1/(Fe/H). In this representation, if there is only a single source with a fixed production ratio of O to Fe beyond a certain point, the subsequent evolution of (O/Fe) is along a straight line segment. Under the assumption of an initial Fe ([Fe/H] ~ -3) and O inventory caused by the prompt production by the first very massive stars, the data of Israelian et al. and Boesgaard et al. at -3≾[Fe/H]≾-1 are interpreted to result from the addition of O and Fe only from Type II supernovae (SNII) to the prompt inventory. At [Fe/H] ≳-1, SNII still contribute O while both SNII and Type Ia supernovae contribute Fe. During this later stage, (O/Fe) sharply drops off to an asymptotic value of ~0.8 (O/Fe)_☉. The value of (O/Fe) for the prompt inventory at [Fe/H] ~ -3 is found to be (O/Fe) ~ 20 (O/Fe)_☉. This result suggests that protogalaxies with low "metallicities" should exhibit high values of (O/Fe). The C/O ratio produced by the first very massive stars is expected to be « 1 so that all the C should be tied up as CO and that C dust and hydrocarbon compounds should be quite rare at epochs corresponding to [Fe/H] ≾ -3.

Item Type:Article
Related URLs:
URLURL TypeDescription
Wasserburg, G. J.0000-0002-7957-8029
Additional Information:© 2001 American Astronomical Society. Received 2000 September 7; accepted 2000 October 23. We would like to thank Garik Israelian for supplying the data of Israelian et al. (1998) and Boesgaard et al. (1999) on the same scale of stellar parameters. Comments by the referee, F. X. Timmes, were very helpful in improving the presentation. This work was supported in part by the Department of Energy under grant DE-FG02-87ER40328 to Y.-Z. Q. and by NASA under grant NAG5-4083 to G. J. W., Caltech Division Contribution No. 8732(1063).
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-87ER40328
Subject Keywords: Galaxy: abundances; Galaxy: evolution; Galaxy: formation; stars: abundances; supernovae: general
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8732
Lunatic Asylum Lab1063
Issue or Number:1
Record Number:CaltechAUTHORS:20131210-143422073
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Official Citation: Evolution of O Abundance Relative to Fe Y.-Z. Qian and G. J. Wasserburg 2001 ApJ 549 337
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42935
Deposited By: Ruth Sustaita
Deposited On:10 Dec 2013 22:55
Last Modified:09 Mar 2020 13:19

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